1. Field of the Invention
The present invention relates to a coupling structure of a band comprising a plurality of piece members such as a band of a wrist watch and to a method of manufacturing the piece member for the coupling structure.
2. Description of the Prior Art
A conventional watch band structure comprises a plurality of piece members that are coupled to each other in a longitudinal direction which can be bent freely in conformity with the shape of a user's arm (see Japanese Laid-Open Utility Model Publications Nos. Sho 50(1975)-50071 and Sho 51(1976)-121368).
In a coupling structure 100 of a watch band, for example, depicted in FIGS. 15 and 16, coupling holes 108 and 110 are formed on coupling ends 104 and 104 on the outside in a transverse direction which are formed on one of the ends of an almost U-shaped piece member 102 and a coupling projection 106 in a central part which is formed on the other end respectively. The coupling projection 106 of one of the piece members 102 is positioned between the coupling ends 104 and 104 of the other piece member 102. Then, an adjust pin 112 energized in a diameter increasing direction, such as a hair pin is inserted as a coupling member in such a state that the coupling holes 108 and 110 of the coupling end 104 and the coupling projection 106 are coincident with each other. Thus, the piece members 102 are coupled to each other in the longitudinal direction in such a manner that the adjust pin 112 does not slip from the coupling holes 108 and 110.
In the case in which the adjust pin energized in the diameter increasing direction, such as the hair pin is used as the coupling member, a coupling pin is removable and the length of a band can be adjusted. In the case in which the coupling pin is used, it is pressed into the coupling hole and is thus fixed unremovably.
In such a coupling structure, however, in the case in which a user practices strenuous sports or a rotation and a twist are always applied to the coupling portion due to use for years, for example, there is a possibility that the coupling member such as the coupling pin 112 might slip from the coupling holes 108 and 110.
Depending on processing precision of the coupling holes 108 and 110 or processing precision of the coupling member such as the coupling pin 112, moreover, there is a possibility that the coupling member such as the coupling pin 112 might slip from the coupling holes 108 and 110.
Furthermore, there is a possibility that the coupling member itself, such as the coupling pin 112, might corrode or might repetitively receive a stress to be broken or to lose elastic force thereof and might thus slip off.
In the case in which the coupling member is thus broken or slips off, the band slips from the user's arm, which is not preferable.
In consideration of the circumstances, it is an object of the present invention to provide a band coupling structure in which a coupling member such as a coupling pin or a hair pin does not slip from a coupling hole even if a user practices strenuous sports or a rotation and a twist are always applied to a coupling portion due to use for years, and to provide a method of manufacturing a piece member for the band coupling structure therefor.
Moreover, it is another object of the present invention to provide a band coupling structure in which a spew or the like is not generated around the coupling hole of a piece member and a finished face such as a mirror finished surface, a hairline, a matte finished surface or a concavo-convex pattern is applied thereto, and external quality is enhanced and a high-class impression is given, and to provide a method of manufacturing the piece member for the band coupling structure therefor.